Question

We have an old legacy app that we need to reverse engineer how it works. (The documentation has gone missing.) Our application is communicating with a 3rd party program using windows messages (WM_xxx).

So first attempt is to start spy++ and look at what messages are sent when certain events occur.
We notice that most events are WM_USER+1025 and similar.

So currently we are planning to start writing down what each WM_USER-message should be. It would be great if we could add that information to spy++ to get more readable data the more work we put in.

It is possible to write some “add-on” to spy++ to tell it how to interpret WM_USER+1025?
(Similar to the CustomEvaluators you could write to the VS6-debugger.)

Regards
Leif

Answer 1

After some more thinking, and reading Pat Brenners post on spy++ internals I realize that it would be darn near impossible to write such a “custom display formater”.

spy++ injects a dll into each monitored process. When a WM_msg is sent or received a hook in the injected dll detects this and passes this information on to the main spy++-process.

To write a custom evaluator that would have to be present in the injected dll (or sucked in from that dll). Which can cause complications normally desired to avoid.

I’ll just do it the “normal” way, of modifying my source code.

/L